Determination of Malathion and α-Endosulfan Residue in Khazar Rice Using Matrix Solid Phase Dispersion and HPLC

An extraction method based on matrix solid phase dispersion (MSPD) and high performance liquid chromatography with UV detection for quantification of two widely used pesticides (Malathion and α-Endosulfan) in Khazar rice from north of Iran were investigated. The ratio of solid phase (adsorbent) to sample, types of eluting solvent and its volume were optimized to achieve the highest recoveries for the analytes. Under the appropriate condition, MSPD extraction of target pesticides from rice sample was carried out through mixing of neutral alumina to rice sample in the ratio of 3:1 and elution of analytes from sample mixture using 16 ml of acetone as eluting solvent. Limit of detection, mean recoveries (n=3) and relative standard deviation for malathion and α-endosulfan were 2.31, 2.27 ppm, 99.04%, 71.70% and 0.73%, 1.89% respectively. Linear dynamic range (LDR) for malathion and -endosulfan were 7.7 – 142.2 ppm and 7.6 – 176.5 ppm, respectively. Standard addition method was used to determine the amount of pesticides residue in the marketed Khazar rice. Malathion was not detected in the marketed rice sample but the amount of α-endosulfan residue was 0.04 μg/g which is lower than the maximum residue limit (MRL) of this pesticide in rice samples.